In Standard Battle for Zendikar, Oath of the Gatewatch, Shadows over Innistrad, and Eldritch Moon have rotated out.
The planeswalker uniqueness rule has been removed and now all walkers past, present, and future will be legendary and subject to the legendary rule.
https://magic.wizards.com/en/articles/archive/feature/ixalan-release-notes-2017-09-15
Another rules change that we haven't see the comprehensive rules entry for yet is pointed at in the card specific rulings for Magus of the Moon in the Iconic Masters release notes and by a WotC staff member on twitter.
https://magic.wizards.com/en/articles/archive/feature/iconic-masters-release-notes-2017-09-11
https://mobile.twitter.com/EliShffrn/status/907274042490609664?dti=179562935428684&fref=gc

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